In recent years, it has been determined that spilled liquid mercury can produce a substantial health hazard by contaminating the surrounding ambient atmosphere with mercury vapor which volatilizes from the spilled liquid mercury. Moreover collecting all the spilled mercury in any particular spill is extremely difficult because of the high surface tension and high density of liquid elemental mercury. It has, however, recently been recognized that relatively small amounts of liquid mercury which can escape collection can result in a mercury vapor level above the safe limits for such mercury contamination. Moreover, such small amounts of mercury which are not collected are susceptible of escaping detection and thus, the amount of mercury will not be reduced to a level sufficient to bring the mercury vapor contamination below the safe level. Thus, it is highly desirable to be able to detect the presence of mercury and mercury vapor in an area in order to reduce the mercury vapor contamination to an absolute minimum since the effects of mercury on the human body are cumulative and thus, prolonged exposure to even minute amounts of mercury vapor or other mercury contamination can result in accumulating sufficient amounts to bridge the safe or toxic levels.